The present invention is directed, in general, to integrated circuits and, more specifically, to a chemical mechanical planarization system including a pad conditioner and a method of making integrated circuits using the chemical mechanical planarization system.
Chemical mechanical planarization (CMP) is an essential process in the manufacture of semiconductor chips today and is becoming more critical as device sizes continue to shrink into the lower submicron ranges. During CMP, the combination of chemical etching and mechanical abrasion produces a flat, precise surface for subsequent depositions of materials and photolithography steps. The polishing pad for CMP is usually made of polyurethane and has small pores to carry the slurry under the wafer. As a result of the polishing process, pad material and slurry residues collect in the pores, plugging them, and reducing the polish rate due to slurry starvation. This also causes the pad to glaze making the surface of the pad smooth. When the pad becomes clogged or glazed, it becomes necessary to xe2x80x9cconditionxe2x80x9d the pad to restore its full functionality. That is, the accumulated material is removed before it completely clogs or glazes the pad.
In many conventional processes, a conditioning wheel comprised of a nickel-chromium alloy with a surface of embedded diamond abrasives is used to condition the pad. The conditioning wheel is pressed against the polishing pad by a conditioning wheel actuator; e.g., a hydraulic arm, and the pad and conditioning wheel are rotated while de-ionized water is flowed to rinse away abraded material. The diamond elements remove embedded particles, slurry, and polishing by-products from the polishing pad. The conditioning proceeds until the pad is xe2x80x9cre-surfacedxe2x80x9d and new pores are exposed.
Conventionally, the conditioning wheel may take various forms: e.g., an annular ring about the carrier head of the chemical mechanical planarization system, nylon brushes, buttons, or a solid planar surface. Establishing and maintaining precise planarity of the conditioning surface as the diamonds wear and break off is a well-known problem that is exaggerated by the small conditioning area (the contact area between the conditioning wheel and the polishing pad). Because the conditioning wheel surface area is only a small fraction of the polishing pad surface area, the conditioning wheel must be moved back and forth over the polishing pad in order to condition the entire pad. This results in local conditioning of the pad. Local conditioning of the pad is a function of conditioning time, the pressure and velocity of the conditioning wheel, and the wear of the conditioning wheel. As a result, conditioning can vary across the polishing pad. Consistency of the polishing environment is, however, a high priority in order to maintain an extremely precise CMP processes from wafer to wafer.
Accordingly, what is needed in the art is an apparatus and method of use that avoids the limitations of the prior art described above.
To address the above-discussed deficiencies of the prior art, the present invention provides a method of manufacturing a semiconductor device employing a polishing pad conditioner that directs a conditioning fluid stream at a polishing pad to remove accumulated material from the pad. The conditioning fluid stream may contact a large area of the polishing pad or a smaller area where the conditioning fluid stream is moved to condition different areas of the polishing pad. The conditioning fluid stream may include abrasive particles to promote the removal of the accumulated materials. The velocity of the conditioning fluid stream may be increased or decreased to promote removal of the accumulated materials. In yet another embodiment, the present invention is directed to a process for manufacturing an integrated circuit using a CMP process where the pad has been conditioned using the conditioning fluid stream. The present invention is also directed to a chemical mechanical planarization system including a pad conditioner.